Commercial boiler repair. Look at boiler system, system kept getting air locked. Turned boiler temperature down to 180*. 3 returns used temperature Gun to balance returns; one is fully open, 2nd return is 1/2 open and the 3rd one is 1/3 way open to balance system so the 3 zones heat even. Check for air in system. Recommend installing boiler air scoop on supply with auto vent. The back of church should have auto vent installed where it jumps below floor. Also may want to install auto vents back in Sanctuary with 1/4 ball valves. May want to install Tekmar controller on system to adjust water temp.